1. Field of the Invention
The present invention relates to new catalyst components for the polymerization of olefin comprising magnesium halide and salt of IB-VIIIB elements, titanium halide and internal donors.
2. Description of the Related Art
The modern Ziegler Nana catalysts comprising magnesium halide, titanium halide and internal donors are well known in art and has been prepared by various methods. One method consists of co-grinding the magnesium halide with internal electron donors until the product shows a surface area higher than 20 m2/g and thereafter reacting the ground product with the Ti compound. These methods of preparing solid Ziegler-Natta type catalyst components are disclosed in U.S. Pat. Nos. 4,220,554; 4,294,721; 4,315,835; 4,330,649; 4,439,540; 4,816,433; and 4,978,648. Another method known in the art describes reaction of titanium tetrachloride compounds with organoaluminum halides in the presence of magnesium halide composite to prepare catalyst components, which is described in U.S. Pat. Nos. 4,330,648; 4,314,911; and 4,474,703; WO/8912649; WO/8600625; and CN 1837247. However, these catalyst components are not satisfactory in terms of polymerization activity and stereo-specificity of resulting polymer chain.
There have also been efforts to achieve balanced catalyst properties in terms of activity and stereo-specificity. Mitsui Petrochemical Industries, Ltd. have published olefin polymerization catalysts employing specific silicon compounds which has improved polymerization activities and stereo-specificity (e.g., U.S. Pat. No. 4,990,479, EP 0350170 B2, and CN 1040379) remarkably compared to those of the conventional catalyst components. The presence of electron donors have also been found to allow preparation of catalyst components endowed not only with high activity, but also with a high stereo-specificity and solid catalysts have been prepared with internal electron donors. Common internal electron donor compounds, incorporated in the solid Ziegler-Natta catalysts components during preparation of such catalysts include ethers, ketones, amines, alcohols, phenols, phosphines, and silanes. Also, external electron donors have been employed simultaneously with solid catalyst components for olefin polymerization to improve stereo-specificity and organosilicon compounds are commonly used as external electron donors. Examples of such catalyst system are described in U.S. Pat. Nos. 4,107,414; 4,186,107; 4,226,963; 4,347,160; 4,382,019; 4,435,550; 4,465,782; 4,522,930; 4,530,912; 4,532,313; 4,560,671; 4,657,882; 5,208,302; 5,902,765; 5,948,872; 6,121,483; and 6,770,586. EP 0361494 B1 discloses solid catalyst components comprising, as an internal donor, 1,3-diether, which is capable of forming complexes with magnesium halide and TiCl4 in such a way that the solid catalyst components can achieve good results in terms of good activity and stereo-specificity. EP 0622380 B2 demonstrates that the solid catalyst components containing 1,3-diether produces polymers having very high melt flow rates with good activity while EP 0728769 B1 refers to electron donors of cyclopolyenic 1,3-diethers conferring a further increase of activity. Notwithstanding the good polymerization activity as well as stereo-specificity of the catalyst components containing various electron donors, the balance of properties still should be improved in terms of catalyst activity and stereo-specificity.